Police were called to ITN’s London headquarters after a group of protesters “unlawfully gained access” to the building.
The protesters are understood to have forced their way into the building on Gray’s Inn Road in Camden following an anti-vaccination and anti-lockdown protest in central London.
Images posted on social media by ITN staff showed dozens of people in the ITN reception, with police standing between them and security barriers into the main building.
Crowds of police were also gathered on the pavement outside to block any more any more demonstrators forcing their way in.
A video circulated on Twitter showed protesters yelling abuse at veteran news anchor Jon Snow as he made his way in.
Following the incident in Camden on Monday, the Metropolitan Police said: “Officers are responding to a demonstration at a private premises on Gray’s Inn Road, Camden, where people have unlawfully gained access to the building.
“Officers are on scene engaging with building security and removing those who have gained entry.”
An ITN spokeswoman said: “The police are attending a breach of security at Gray’s Inn Road, ITN’s headquarters.
“ITN staff including those working in ITV News, Channel 4 News and 5 News have been advised to either stay in the building or stay away while the situation is being dealt with.
“News organisations have provided a vital source of information during the pandemic.
“The abuse of journalists because of their reporting on coronavirus is a worrying development which ITN has been closely monitoring and actively ensuring staff are aware of precautions to avoid coming to any harm.
“This action resulted in journalists being prevented from being able to go about their newsgathering activities, something that ITN strongly condemns.”
It follows an incident on August 9 when a crowd thought to be made up of anti-vaxx protesters tried to gain access to the BBC’s old headquarters in White City, west London.
The premises is now used to film ITV’s talk show Loose Women.